BIOLOGICAL DEATH AND REPRODUCTION 



higher organism dies, the somatic mutation damage 

 accumulated in most of the tissues of the organism may 

 be quite low. However in higher organisms, the 

 dependence of all the cells upon certain specialized 

 organs is quite complete. Furthermore the rate of 

 fission in cells and cell growth, which largely deter- 

 mines the extent to which mutation damage is kept 

 under control, is dependent on various specialized or- 

 gans, such as the glands that determine the general 

 cell metabolism. Consequently mutation damage need 

 only seriously affect certain, especially sensitive groups 

 of cells, in order to start an accumulative degenerative 

 process. This situation may account for the greatly 

 varying life spans of the various species, as well as for 

 the fact that the process of aging in the higher species 

 is at first slow, but proceeds with much greater speed 

 at the end of the natural life span. 



The theory that natural death in metazoa is a result 

 of the direct or indirect effects of somatic mutations 

 has some bearing on the problem of cancer. Death 

 from cancer, can of course not be considered natural 

 death in the way in which one may regard death at very 

 old age. However there is considerable evidence that 

 cancer originates because some very specific mutations 

 have taken place in some cells of the organism, (per- 

 haps only in one cell) . The mutations producing 

 cancer are of a very special nature, altering function of 

 the cell, rather than just producing disorganization 



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